Preface

Modern systems necessitate the use of advanced materials with appropriate surface properties essential to enhance their performance significantly. A surface that is exposed directly to different environments depending on the application is paramount because it needs to exhibit excellent resistance against wear, erosion, corrosion, temperature, pressure, etc. to improve durability and achieve ever-greater efficiency. Therefore, there is a need to obtain an appropriate surface finish depending on the application, which necessitates the usage of multiple surface engineering techniques that are complementary to each other in association with suitable surface preparation processes. To ensure the expected behavior and efficiency, modern experimental methods to assess surface characteristics as well as interfaces are of great importance. This book presents recent advances in the field of surface science for a better understanding of surfaces and interfaces and their applications. It is a useful book describing a variety of materials for different applications and gives an in-depth understanding of mechanisms involved in achieving the desired properties that are extremely useful to materials developers, design engineers, scientists, system maintenance engineers, academia, students, researchers, and industrialists. The book comprises a collection of articles written by senior people specialized in surface science and technologies.

Chapter 1 covers organic semiconductors as active materials in thin film electronic devices, such as alkynes, heterocyclics, dyes, ferrocenes, spiranes, or porphyrins, with special geometries and certain electronic molecular parameters that possess nonlinear optical properties and offer several major advantages over their inorganic counterparts. There are a number of simple and versatile techniques that can be employed for the deposition of these important classes of materials. The matrixassisted pulsed laser evaporation (MAPLE) technique provides advantages with regard to making organic films of different morphologies on various types of substrates. New insights into crystallization growth mechanisms in MAPLE-deposited conjugated polymer films, which realize the connection between the structure and the carrier transport properties, are discussed herein. Second harmonic generation capabilities of thin films are also investigated.

Chapter 2 demonstrates different proposals of magnetic bioderivatives and their applicability in biotechnology. The historical context of immobilized enzymes, as well as immobilization methods highlighting the main advantages and disadvantages of each, is mentioned. In addition, iron oxides and composite materials are presented as support for biomolecule immobilization. Composites are effortlessly prepared, including many materials capable of providing advantages to the magnetic derivatives. Enzymes covalently linked to these magnetic particles combine their catalytic properties with reaction specificity, reusability, and possible reactor construction. In addition, proteins can also be purified by these magnetic composites containing specific ligands allowing reactors and reuses too. A number of characterization techniques used to study the magnetic material and derivative immobilized are described as well. Altogether, an engaging presentation of the interesting features of magnetic bioderivatives is highlighted, as well as their uses in the biotechnology field and other applications.

Chapter 3 discusses surface science engineering through the sol-gel process and its significance. Sol-gel synthesis is used to obtain coatings that can modify the surfaces of metals to avoid corrosion or to enhance the biocompatibility and bioactivity of metals and their alloys that are of biomedical interest. Anticorrosion coatings composed of smart coatings and self-healing coatings are described. TiO2, hydroxyapatite, bioglass, and hybrid coatings synthesized by sol-gel technology are briefly introduced with regard to their role in modifying the surface of metals for biomedical purposes. Finally, although there are other approaches to modify the surface of metals for either anticorrosion or biomedical purposes, sol-gel methods have several advantages in controlling surface chemistry composition and functionality.

Chapter 4 describes the synthesis, characterization, and adsorption properties of nanoporous materials: nitroprussides, Prussian blue analogs, akaganeites, MeAPOs, metal organic frameworks, and highly specific surface amorphous silica, which allow the storage of about 11 wt% of hydrogen in the form of ammonia. In this sense, the use of solid-state reaction method and sol-gel methodologies, together with aluminosilicate, high silica, and non-aluminosilicate zeolite synthesis methods, is described. Moreover, the preparation of active carbons along with the synthesis of Prussian blue analogs and nitroprussides is explained. In addition, characterization of the materials of interest applying X-ray diffraction, thermogravimetric analysis, DRIFTS, and room-temperature Mossbauer spectrometry is discussed. Besides, were defined the concepts which define physical adsorption, provided examples of adsorption data, which were tested with the help of the Dubinin, osmotic adsorption, and Langmuir-type isotherms. Additionally, the methodology for the measurement of adsorption data with the help of the volumetric method is described. Moreover, a description of the thermodynamics of adsorption, as well as the methodology for the calculation of calorimetric data with the help of heat flow calorimeters together with the measurement of differential heats of adsorption data, is analyzed. Finally, the different interaction forces that make adsorption possible are discussed.

Chapter 5 presents ternary alloys of cobalt with molybdenum and tungsten deposited from biligand citrate-pyrophosphate electrolytes by the pulsed mode, which exhibits different compositions and surface morphologies depending on current density and on/off time. It is shown that the current density of 910 A dm2 and on/ off time of 5/20 ms favor the maximum refractory metals content in the deposits, but increasing current density diminishes the efficiency of electrolysis. When depositing Co-Mo-W from the electrolyte, the ratio Mo:W is 1:2 and tungsten content in the alloy is found to be much lower in comparison with molybdenum: W 27 at% vs. Mo 16 22 at%; the total of Mo + W content is 1527 at%. Therefore, changing the concentrations of Mo and W salts in the electrolyte for Co-Mo-W alloy deposition does not influence Mo and W content in the deposit in the same proportions. It is established that a sufficiently uniform surface of binary Co-Mo and Co-W deposits with smaller spheroid sizes and without microcracks may be attributed to lower refractory metals content. The structure of binary and ternary alloys is found to be amorphous crystalline, and intermetallic phases Co7W6 and Co7Mo3 are identified in deposits. The coherent-scattering region size of the amorphous part is detected at 2–8 nm. The amorphous structure of ternary alloys and significant content of alloying elements (Mo and W) predetermine improved high corrosion resistance. Corrosion resistance of binary and ternary deposits increases with the total content of refractory metals, which, associated with molybdenum and tungsten, enhance corrosion resistance to pitting as well as decrease roughness and smooth out the relief of ternary coatings. Ternary galvanic alloys of cobalt with molybdenum and

**V**

of 46 A dm2

as well as the acid nature of their oxides.

is most satisfactory because correlation coefficient (R2

postgraduate students, and industrialists.

significant effect on SR.

zirconium of different compositions and morphologies are obtained from polyligand citrate-pyrophosphate electrolytes in a pulsed mode by varying the current density and duration of pulse and pause. It is shown that coatings with microglobular morphology with a low level of stress and cracks are formed at a current density

ternary coatings based on cobalt is caused by an increased tendency to passivity and high resistance to pitting corrosion in the presence of molybdenum and zirconium,

Chapter 6 describes the attempts made to investigate the experimental process and surface roughness (SR) optimization of cold working (high carbon and high omium) hard die steel (D2) during the wire electrical discharge machining (WEDM) processes. The WEDM process relies heavily on the operators' technologies and experience because of their numerous and diverse range. Because using complicated cuts can make it difficult to machine electrically conductive components, the WEDM process was developed to generate precise cutting on complicated and difficult to machine materials. Tan-sigmoid and purlin transfer function with a bias-based four-layered back propagation artificial neural network approach have been used to investigate the effect of six independent parameters, namely gap voltage (Vg), flush rate (Fr), pulse on time (Ton), pulse off time (Toff), wire feed (Wf), and wire tension (Wt) over the Center Line Average value of surface roughness (Ra) along with corresponding material removal rate (MRR). Model adequacy

the adjusted (Radj.2) statistics is 98.5. It was found that the spark time ON/OFF, wire feed rate, wire tension, gap voltage, flush rate and a few of their interactions have a

I strongly believe that this book will be useful to materials scientists, system design engineers, manufacturing experts and executives, mechanical engineers, chemical engineers, aeronautical engineers, academic researchers, undergraduate and

and polarization on/off time of 2/10 ms. High corrosion resistance of

) is found to be 99.1% and

**Dr. Gurrappa Injeti**

Hyderabad, India

Defence Metallurgical Research Laboratory,

Professor,

zirconium of different compositions and morphologies are obtained from polyligand citrate-pyrophosphate electrolytes in a pulsed mode by varying the current density and duration of pulse and pause. It is shown that coatings with microglobular morphology with a low level of stress and cracks are formed at a current density of 46 A dm2 and polarization on/off time of 2/10 ms. High corrosion resistance of ternary coatings based on cobalt is caused by an increased tendency to passivity and high resistance to pitting corrosion in the presence of molybdenum and zirconium, as well as the acid nature of their oxides.

Chapter 6 describes the attempts made to investigate the experimental process and surface roughness (SR) optimization of cold working (high carbon and high omium) hard die steel (D2) during the wire electrical discharge machining (WEDM) processes. The WEDM process relies heavily on the operators' technologies and experience because of their numerous and diverse range. Because using complicated cuts can make it difficult to machine electrically conductive components, the WEDM process was developed to generate precise cutting on complicated and difficult to machine materials. Tan-sigmoid and purlin transfer function with a bias-based four-layered back propagation artificial neural network approach have been used to investigate the effect of six independent parameters, namely gap voltage (Vg), flush rate (Fr), pulse on time (Ton), pulse off time (Toff), wire feed (Wf), and wire tension (Wt) over the Center Line Average value of surface roughness (Ra) along with corresponding material removal rate (MRR). Model adequacy is most satisfactory because correlation coefficient (R2 ) is found to be 99.1% and the adjusted (Radj.2) statistics is 98.5. It was found that the spark time ON/OFF, wire feed rate, wire tension, gap voltage, flush rate and a few of their interactions have a significant effect on SR.

I strongly believe that this book will be useful to materials scientists, system design engineers, manufacturing experts and executives, mechanical engineers, chemical engineers, aeronautical engineers, academic researchers, undergraduate and postgraduate students, and industrialists.

> **Dr. Gurrappa Injeti** Professor, Defence Metallurgical Research Laboratory, Hyderabad, India

**IV**

adsorption possible are discussed.

Chapter 3 discusses surface science engineering through the sol-gel process and its significance. Sol-gel synthesis is used to obtain coatings that can modify the surfaces of metals to avoid corrosion or to enhance the biocompatibility and bioactivity of metals and their alloys that are of biomedical interest. Anticorrosion coatings composed of smart coatings and self-healing coatings are described. TiO2, hydroxyapatite, bioglass, and hybrid coatings synthesized by sol-gel technology are briefly introduced with regard to their role in modifying the surface of metals for biomedical purposes. Finally, although there are other approaches to modify the surface of metals for either anticorrosion or biomedical purposes, sol-gel methods have several advantages in controlling surface chemistry composition and functionality.

Chapter 4 describes the synthesis, characterization, and adsorption properties of nanoporous materials: nitroprussides, Prussian blue analogs, akaganeites, MeAPOs, metal organic frameworks, and highly specific surface amorphous silica, which allow the storage of about 11 wt% of hydrogen in the form of ammonia. In this sense, the use of solid-state reaction method and sol-gel methodologies, together with aluminosilicate, high silica, and non-aluminosilicate zeolite synthesis methods, is described. Moreover, the preparation of active carbons along with the synthesis of Prussian blue analogs and nitroprussides is explained. In addition, characterization of the materials of interest applying X-ray diffraction, thermogravimetric analysis, DRIFTS, and room-temperature Mossbauer spectrometry is discussed. Besides, were defined the concepts which define physical adsorption, provided examples of adsorption data, which were tested with the help of the Dubinin, osmotic adsorption, and Langmuir-type isotherms. Additionally, the methodology for the measurement of adsorption data with the help of the volumetric method is described. Moreover, a description of the thermodynamics of adsorption, as well as the methodology for the calculation of calorimetric data with the help of heat flow calorimeters together with the measurement of differential heats of adsorption data, is analyzed. Finally, the different interaction forces that make

Chapter 5 presents ternary alloys of cobalt with molybdenum and tungsten deposited from biligand citrate-pyrophosphate electrolytes by the pulsed mode, which exhibits different compositions and surface morphologies depending on current density and on/off time. It is shown that the current density of 910 A dm2

off time of 5/20 ms favor the maximum refractory metals content in the deposits, but increasing current density diminishes the efficiency of electrolysis. When depositing Co-Mo-W from the electrolyte, the ratio Mo:W is 1:2 and tungsten content in the alloy is found to be much lower in comparison with molybdenum: W 27 at% vs. Mo 16 22 at%; the total of Mo + W content is 1527 at%. Therefore, changing the concentrations of Mo and W salts in the electrolyte for Co-Mo-W alloy deposition does not influence Mo and W content in the deposit in the same proportions. It is established that a sufficiently uniform surface of binary Co-Mo and Co-W deposits with smaller spheroid sizes and without microcracks may be attributed to lower refractory metals content. The structure of binary and ternary alloys is found to be amorphous crystalline, and intermetallic phases Co7W6 and Co7Mo3 are identified in deposits. The coherent-scattering region size of the amorphous part is detected at 2–8 nm. The amorphous structure of ternary alloys and significant content of alloying elements (Mo and W) predetermine improved high corrosion resistance. Corrosion resistance of binary and ternary deposits increases with the total content of refractory metals, which, associated with molybdenum and tungsten, enhance corrosion resistance to pitting as well as decrease roughness and smooth out the relief of ternary coatings. Ternary galvanic alloys of cobalt with molybdenum and

and on/

Chapter 1

Abstract

Maria Marinescu

were also investigated.

thin films

1

1. Introduction

desired nonlinear optic properties [9–31].

Synthesis and Nonlinear Optical

Laser-Deposited Films

Studies on Organic Compounds in

Organic semiconductors as active materials in thin-film electronic devices such as alkynes, heterocycles, dyes, ferrocenes, spiranes, or porphyrins, with special geometries and certain electronic molecular parameters, which possess nonlinear optical (NLO) properties and offer several major advantages over their inorganic counterparts, are presented in this chapter. There are a number of simple and versatile techniques that can be employed for the deposition of these important classes of materials. The matrix-assisted pulsed laser evaporation (MAPLE) technique provides advantages with regard to making organic films of different morphologies on different types of substrates. New insights into the crystallization growth mechanisms in MAPLE-deposited conjugated polymer films, which realize the connection between the structure and the carrier transport properties, are discussed herein. Second harmonic generation (SHG) capabilities of the thin films

Keywords: organic synthesis, laser deposition, nonlinear optical properties,

During the last decades, the nonlinear optical (NLO) materials have gained significant role because of their various applications in medicine, molecular switches, luminescent materials, laser technology, spectroscopic and electrochemical sensors, data storage, microfabrication and imaging, modulation of optical signals, and telecommunication [1–3]. Organic materials are distinguished by the fact that they exhibit strong nonlinear optical (NLO) properties [4–8]. In the last years, researchers have based on the synthesis of the target organic molecules with particular geometries and certain electronic molecular parameters, in order to have the

The changes of optical properties (absorption coefficient, index of refraction),

through the increasing intensity of the input light, led to the discovery of the nonlinear optical phenomenon, second harmonic generation (SHG), detectable only after the improvement of the laser in 1962 [32]. Thus, nonlinear optics developed as a tremendous field of research, especially after the profound understanding of nonlinear optic phenomena (NLO) and the structure-property relations of
