Thermophysical Properties of NbAlO4 and TaAlO4

• DOI: 10.1007/s10765-025-03512-w
• Publication Date: 2025-02-08T02:59:16Z
• Authors: Julian Gebauer; Magnus Rohde; Peter Franke; Hans Jürgen Seifert

Abstract Thermophysical properties of the ternary oxides NbAlO4 and TaAlO4 are experimentally determined. For NbAlO4, the molar heat capacity is 98.9 J (mol

$$\cdot$$

·

K)−1 at 0

$$^{\circ }$$

∘

C up to 155.6 J (mol

$$\cdot$$

·

K)−1 at 950

$$^{\circ }$$

∘

C and for TaAlO4 97.1 J (mol

$$\cdot$$

·

K)−1 at 0

$$^{\circ }$$

∘

C up to 154.2 J (mol

$$\cdot$$

·

K)−1 at 950

$$^{\circ }$$

∘

C, respectively. Maier-Kelley polynomials are provided for the molar heat capacities. Thermal diffusivities in the range from 20

$$^{\circ }$$

∘

C to 700

$$^{\circ }$$

∘

C (

$$\alpha _{NbAlO_{4}}$$

α

N b A l

O 4

: from 0.009 to 0.004 cm2·s−1 and

$$\alpha _{TaAlO_{4}}$$

α

T a A l

O 4

: from 0.017 to 0.005 cm2·s−1), bulk densities at 25

$$^{\circ }$$

∘

C (

$$\rho _{NbAlO_{4}}$$

ρ

N b A l

O 4

= 3.94 g

$$\cdot$$

·

cm−3 and

$$\rho _{TaAlO_{4}}$$

ρ

T a A l

O 4

= 6.07 g·cm−3) and melting points of the oxides are measured, and the thermal conductivities are calculated from these properties. The thermal conductivity from 20

$$^{\circ }$$

∘

C to 700

$$^{\circ }$$

∘

C of NbAlO4

$$\lambda _{ NbAlO_{4}}$$

λ

N b A l

O 4

is in the range from 0.020 to 0.013 W·cm−1·K−1 and of TaAlO4

$$\lambda _{TaAlO_{4}}$$

λ

T a A l

O 4

in the range from 0.039 to 0.015 W·cm−1·K−1, respectively. A porosity correction for thermal conductivities is applied, and with that, data for perfectly dense material are provided.