Phase Relations and Thermal Expansion in the System HfO<sub>2</sub>‐TiO<sub>2</sub>

Ruh, Robert; Hollenberg, G.W.; Charles, E.; Patel, V. A.

doi:10.1111/j.1151-2916.1976.tb09416.x

Cited by 45 publications

(13 citation statements)

References 7 publications

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“…Such orthorhombic-HfTiO 4 crystal phase can occur only at the specified range of the Ti-Hf ratio, i.e. for compounds where titanium content is higher than 36 at% and lower than 53 at% [25,46]. Further annealing of (Hf 0.52 Ti 0.48 )Ox coating at 700 °C caused complete crystallization with peaks related to other HfTiO 4 crystal planes.…”

Section: Resultsmentioning

confidence: 99%

The effect of post-process annealing on optical and electrical properties of mixed HfO2–TiO2 thin film coatings

Obstarczyk

Kaczmarek

Mazur

et al. 2019

J Mater Sci: Mater Electron

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In this paper a comparison of electrical and optical properties of mixed hafnium-titanium oxides is described. Thin films were deposited with the use of the magnetron co-sputtering method. For further analysis (Hf 0.52 Ti 0.48)Ox and (Hf 0.29 Ti 0.71) Ox coatings, which were amorphous directly after the deposition process, were chosen,. Moreover, post-process annealing was also performed in order to compare the electrical and optical properties of amorphous and nanocrystalline thin films with the same material composition. It was found that the phase transition from amorphous to orthorhombic HfTiO 4 occurred in the case of (Hf 0.52 Ti 0.48)Ox coating at 650 °C. In turn, the phase transition to TiO 2-anatase was observed at the temperature of 600 °C in the case of (Hf 0.29 Ti 0.71)Ox thin film. The leakage current for both amorphous coatings was in the range of 10 −7-10 −8 A/cm 2. After additional annealing and phase transition, the leakage current slightly decreased for (Hf 0.29 Ti 0.71)Ox thin film, while in the case of (Hf 0.52 Ti 0.48)Ox sample the resistance switching effect was observed. The dielectric constant was equal to 24 and 25 for amorphous (Hf 0.52 Ti 0.48)Ox and (Hf 0.29 Ti 0.71)Ox films, respectively. However, after the phase transition it decreased to 15 for (Hf 0.52 Ti 0.48)Ox and increased to 51 for (Hf 0.29 Ti 0.71)Ox film. The results of optical studies showed that amorphous thin films were well transparent in a visible light range with an average transparency of ca. 85%. After the phase transition to HfTiO 4-orthorhombic and TiO 2-anatase, a slight decrease in the transparency level by 3% and a redshift of the cutoff wavelength was observed. Moreover, additional annealing caused small changes of the optical band gap energy, refractive index and extinction coefficient.

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Section: Resultsmentioning

confidence: 99%

The effect of post-process annealing on optical and electrical properties of mixed HfO2–TiO2 thin film coatings

Obstarczyk

Kaczmarek

Mazur

et al. 2019

J Mater Sci: Mater Electron

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“…The rapid cooling rates experienced by the samples can contribute to retained t‐HfO 2 . t‐HfO 2 in the SiC S /BN/HfB 2 ‐SiC can also be attributed to Ti‐stabilized t‐HfO 2 which would suggest the sample saw temperatures of at least 1630°C …”

Section: Results and Analysismentioning

confidence: 99%

Oxidation of SiC_f/SiC‐HfB₂ Composites under Laser Heating

Carney

Leslie

Jones

2015

Int J Applied Ceramic Tech

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Ceramic matrix composites with Sylramic TM and CG Nicalon TM SiC fibers and SiC-HfB 2 matrices derived from a combination of polymer-derived SiC ceramic and HfB 2 particulate slurries were prepared. The composites were tested for oxidation resistance by laser heating at 2 MW/m 2 to achieve temperatures near 1600°C. The oxidation resistance was compared between uncoated CG Nicalon TM and BN-coated Sylramic TM fiber-based composites. Oxidation resulted in precipitated nano-sized HfO 2 independent of the fibers and fiber coatings.

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“…For example, the monoclinic-tetragonal phase transition occurs at a higher temperature and the accompanying volume change (3.4%) is smaller, potentially making it a far better refractory material. In addition, it has been demonstrated (Ruh et al 1976) that selected Hf0 2based ceramic compositions possess zero or very low thermal expansion coefficients, but there have been no reports of the technological exploitation of this property. The principal applications of zirconia are: refractories, abrasives, ceramic colors, piezoelectrics, capacitors, pyroelectrics, ceramics, ceramic heating elements, thermal barrier coatings, ceramic fibers, solid electrolytes, glass, gemstones and catalysts (Farnworth et al 1981).…”

Section: Applicationsmentioning

confidence: 99%