**10.3.1. Alkaline aluminum phosphate glasses**

Various types of oil-well cements are distinguished. The most important is the phase compo‐ sition of cement, primarily the C3A phase content, which causes quick paste thickening. The main feature of oil-well cement is that it must remain sufficiently fluid for a long period, required for its pumping to deep well. Simultaneously, the temperature in the borehole

American Petroleum Institute (API) are introduced by Clinkers containing limestone loess, diatomite, pyritic ash and sand modified with gypsum and apatite were used for the manu‐ facture of heat resistant oil-well cements. Apatite is also a good stabilizer for high belite

A Same as ASTM Type I Well depths up to 1800 m and temperatures of 27 – 77°C.

D Low C3A with set retarder Depths up to 1800 – 3600 m and temperatures of

E Depths up to 1800 – 4200 m and temperatures of

F Depths up to 3000 – 4800 m and temperatures of

J Essentially β-C2S and pulverized silica sand Depths below 6000 m and temperatures > 177°C

In the past decades, optical waveguides have raised great interest, as they are the most fundamental and integral part of integrated optic circuits. Glass-based integrated optical devices have several obvious advantages over other technologies such as low intrinsic absorption in near-infrared region of the spectrum, minimized coupling losses to optical fibers and no intrinsic material birefringence compared to crystalline semiconductors. Phosphate glasses are regarded as excellent glass host for the waveguide laser fabrication mainly because of high solubility of rare-earth ions compared to other oxide glasses, which allows for high doping concentrations without significant lifetime reduction, resulting in high gain in short waveguides or cavities and a desirable feature in single-frequency lasers. High-performance

G and H Coarse-ground ASTM Types II and IV Temperatures of 27 – 93°C.

The rate depends on the geothermal degree, which in Europe is about 33 m·°C−1 [48].

77 – 138°C.

77 – 138°C.

127 – 160°C.

**API classSpecial properties Intended use**

464 Apatites and their Synthetic Analogues - Synthesis, Structure, Properties and Applications

B Similar to ASTM Type II, low C3A, high sulfate

C Similar to ASTM Type III, low C3A, high sulfate

**Table 2** Types and properties of oil-well cements [49].

**10.3. Phosphate glasses and glass-ceramics**

[48],[49]. The types and properties of oil-well cements specified by the

Well depths up to 1800 m and temperatures of 80 – 170°C.

increases with depth6

resistance

resistance

6

cements [50].

Alkaline aluminum phosphate glasses (NMAP) with excellent chemical durability for thermal ion-exchanged optical waveguide were investigated by WANG et al [51]. The transition temperature (*T*g = 470°C) is higher than the ion-exchange temperature (390°C), which is favorable for sustaining the stability of the glass structure for planar waveguide fabrication. The glass-forming region in the Na2O-Al2O3-P2O5 system is shown in **Fig. 6** [51],[58].

**Fig. 6.** Ternary phase diagram of Na2O-Al2O3-P2O5 system [51],[58].

## **10.3.2. Iron phosphate glasses**

Iron phosphate glass is a versatile matrix for the immobilization of various radioactive elements found in high-level nuclear waste (HLW). Among various compositions of iron phosphate glass, the one with 40 mol.% Fe2O3-60 mol.% P2O5 was found to be chemically durable. It also has the ability to accommodate large amounts of certain nuclear wastes, especially those that are not well suited for borosilicate glasses. Better chemical durability of iron phosphate glass is attributed to the presence of more hydration-resistant Fe-O-P bonds compared to P-O-P bonds available in other phosphate glasses [59],[60],[61].

## **10.3.3. Lithium vanado-phosphate glasses**

Lithium vanado-phosphate (LiVP) glasses have been largely studied due to their potential application as cathode materials as a result of mixed electronic-ionic conductivity character.7 Furthermore, lithium and vanadium structural rearrangements in the glass matrix could modify the transport properties of the systems. Interestingly, the modifier ions depolymer‐ ize the glass network, creating useful channels that enhance the ionic conductivity, but they can also break some V4+/O/V5+ linkages that are essential to the electronic conductivity because they are supposed to be the preferential path for small polaron hopping. The population of

<sup>7</sup> Fast ion conducting (FIC) phosphate glasses have become very important due to a wide range of applications in solidstate devices [63].

V4+/O/V5+ paths depends even on the V/P ratio and it can modify the main structure role of vanadium ions in glasses [62],[63],[64].
