Thermal Expansion of HfO<sub>2</sub> and ZrO<sub>2</sub>

Haggerty, R.; Sarin, P.; Apostolov, Zlatomir D.; Driemeyer, Patrick E.; Kriven, Waltraud M.

doi:10.1111/jace.12975

Cited by 115 publications

(63 citation statements)

References 28 publications

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“…The resulting LTEC α is an increasing function of temperature and coincides with values known from literature for temperatures between 1200 K -1800 K [5,7]. The experiments in this paper expand the range of the studied values of T for almost 1000 K above the temperatures.…”

Section: Resultssupporting

confidence: 88%

Investigation of the thermal expansion of the refractory materials at high temperatures

Kostanovskiy

Kostanovskaya

Zeodinov

et al. 2017

J. Phys.: Conf. Ser.

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Section: Resultssupporting

confidence: 88%

Investigation of the thermal expansion of the refractory materials at high temperatures

Kostanovskiy

Kostanovskaya

Zeodinov

et al. 2017

J. Phys.: Conf. Ser.

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“…Figure 2a shows the in situ XRD data acquired using a Bragg-Brentano (BB) geometry from the aforementioned four steps, and Figure 2b depicts the applied temperature as a function of time on the same scale. [27,48] The strongest change can be observed during the second heating step up to 900 °C as seen in Figure 2a. However, the relative intensities of diffraction peaks from the m-phase were lower compared to the results obtained on ferroelectric, doped HfO 2 thin films in Figure S1 of the Supporting Information.…”

Section: Wwwadvelectronicmatdementioning

confidence: 95%

Effect of Annealing Ferroelectric HfO₂ Thin Films: In Situ, High Temperature X‐Ray Diffraction

Park

Chung

Schenk

et al. 2018

Adv Elect Materials

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crystalline phase in doped HfO 2 thin film. [17,18] However, this phase cannot be observed in the phase diagram of bulk HfO 2 and ZrO 2 , [19,20] even when doped with elements that are used in the thin film counterparts. [21] Therefore, multiple factors were suggested as origin of the stabilization of the ferroelectric phase. Materlik et al. suggested that the o-phase can be stabilized due to surface energy effects, [22] and Park et al. comprehensively examined the surface energy model and their experimental observations. [23] In the latter study, it was confirmed that the o-phase can be stabilized within the nuclei formed during the atomic layer deposition (ALD) process, but the interface/grain boundary effect is not sufficient to stabilize the o-phase within the final grain size after annealing. [23] Therefore, it was suggested that the crystalline phase of the initial nuclei can remain even after crystallization, implying that the phase transformation to the monoclinic phase (m-phase, space group: P2 1 /c) can be kinetically suppressed. [23,24] Stress in thin films was also suggested as a possible origin, [1,25,26] and Shiraishi et al. experimentally proved that the polymorphism of Hf 0.5 Zr 0.5 O 2 thin films is strongly affected by the thermal expansion coefficient (TEC) of the used substrate. [27] However, the detailed mechanism of the formation of the unexpected o-phase is not yet resolved.It is generally known that the structure and electrical properties of perovskite ferroelectrics are strongly coupled. [28][29][30] The ferroelectric properties of doped HfO 2 thin films are also believed to be determined by their crystalline structure. ParkThe ferroelectricity in fluorite oxides has gained increasing interest due to its promising properties for multiple applications in semiconductor as well as energy devices. The structural origin of the unexpected ferroelectricity is now believed to be the formation of a non-centrosymmetric orthorhombic phase with the space group of Pca2 1 . However, the factors driving the formation of the ferroelectric phase are still under debate. In this study, to understand the effect of annealing temperature, the crystallization process of doped HfO 2 thin films is analyzed using in situ, high-temperature X-ray diffraction. The change in phase fractions in a multiphase system accompanied with the unit cell volume increase during annealing could be directly observed from X-ray diffraction analyses, and the observations give an information toward understanding the effect of annealing temperature on the structure and electrical properties. A strong coupling between the structure and the electrical properties is reconfirmed from this result.

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“…HfO 2 is usually regarded as a higher‐temperature substitute for ZrO 2 , mainly owing to the similarities in the chemical, physical, and structural properties, which is attributed to the similar atomic and ionic radii of Zr and Hf . The behaviors of hafnia and zirconia in the temperature range up to 1800 °C have been extensively studied with various techniques such as X‐ray diffraction (XRD), differential thermal analysis, dilatometry, etc. However, no extensive experimental studies have been performed on hafnia under extremely high temperatures 1800 °C to the melting temperature.…”

Section: Introductionmentioning

confidence: 99%

“…The behaviors of hafnia and zirconia in the temperature range up to 1800 °C have been extensively studied with various techniques such as X‐ray diffraction (XRD), differential thermal analysis, dilatometry, etc. However, no extensive experimental studies have been performed on hafnia under extremely high temperatures 1800 °C to the melting temperature. HfO 2 exists in three polymorphs at atmospheric pressure.…”

Section: Introductionmentioning

confidence: 99%

“…At a low temperature, hafnia is stable in a monoclinic baddeleyite phase (space group P 2 1 / c ) . At a temperature of ≈1727 °C, a phase transition from the monoclinic phase to tetragonal (space group P 4 2 / nmc ) phase is observed . At a temperature of ≈2597 °C, the tetragonal phase transforms into a cubic fluorite structure (space group Fm 3 m ) .…”

Section: Introductionmentioning

confidence: 99%

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Pre‐Transitional Behavior in Tetragonal to Cubic Phase Transition in HfO₂ Revealed by High Temperature Diffraction Experiments

Tobase

Yoshiasa

Arima

et al. 2018

Physica Status Solidi (b)

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Using the container‐less levitation technique, high‐temperature X‐ray diffraction experiments have been performed on HfO2 powders to confirm the temperature dependences of the lattice constants, thermal expansion character, and phase relations. A two‐dimensional imaging plate detector is used for short‐time observations; diffraction data in a wide area are projected in one dimension for Rietveld analysis, as large‐grain growth occurred at high temperatures. The lattice constants, thermal expansions, and c/a ratios for the tetragonal (space group P42/nmc) and cubic (space group Fm3m) HfO2 phases are measured at high temperature. The transition temperature of HfO2 from the tetragonal phase to the cubic phase is specified to be between 2500 and 2550 °C. The pre‐transitional behavior is clearly observed around 2200 °C. As no clear lattice volume change is observed at the transition point from the tetragonal phase to the cubic phase, a phase boundary between the tetragonal phase and the cubic phase has been proposed which does not exhibit a negative slope. It has been estimated that the stable region of the cubic phase is narrow in the higher‐pressure region.

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Thermal Expansion of HfO₂ and ZrO₂

Cited by 115 publications

References 28 publications

Investigation of the thermal expansion of the refractory materials at high temperatures

Investigation of the thermal expansion of the refractory materials at high temperatures

Effect of Annealing Ferroelectric HfO₂ Thin Films: In Situ, High Temperature X‐Ray Diffraction

Pre‐Transitional Behavior in Tetragonal to Cubic Phase Transition in HfO₂ Revealed by High Temperature Diffraction Experiments

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Thermal Expansion of HfO2 and ZrO2

Cited by 115 publications

References 28 publications

Investigation of the thermal expansion of the refractory materials at high temperatures

Investigation of the thermal expansion of the refractory materials at high temperatures

Effect of Annealing Ferroelectric HfO2 Thin Films: In Situ, High Temperature X‐Ray Diffraction

Pre‐Transitional Behavior in Tetragonal to Cubic Phase Transition in HfO2 Revealed by High Temperature Diffraction Experiments

Contact Info

Product

Resources

About

Thermal Expansion of HfO₂ and ZrO₂

Effect of Annealing Ferroelectric HfO₂ Thin Films: In Situ, High Temperature X‐Ray Diffraction

Pre‐Transitional Behavior in Tetragonal to Cubic Phase Transition in HfO₂ Revealed by High Temperature Diffraction Experiments