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ZrO2 is Fluorite structured and crystallizes in the cubic Fm-3m space group. The structure is three-dimensional. Zr4+ is bonded in a body-centered cubic geometry to eight equivalent O2- atoms. All Zr–O bond lengths are 2.23 Å. O2- is bonded to four equivalent Zr4+ atoms to form a mixture of edge and corner-sharing OZr4 tetrahedra.
ZrO2 crystallizes in the tetragonal P4_2/nmc space group. The structure is three-dimensional. Zr4+ is bonded in a distorted body-centered cubic geometry to eight equivalent O2- atoms. There are four shorter (2.09 Å) and four longer (2.44 Å) Zr–O bond lengths. O2- is bonded to four equivalent Zr4+ atoms to form a mixture of distorted edge and corner-sharing OZr4 tetrahedra.
ZrO2 is Baddeleyite structured and crystallizes in the monoclinic P2_1/c space group. The structure is three-dimensional. Zr4+ is bonded to seven O2- atoms to form a mixture of distorted corner and edge-sharing ZrO7 pentagonal bipyramids. There are a spread of Zr–O bond distances ranging from 2.07–2.31 Å. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted trigonal non-coplanar geometry to three equivalent Zr4+ atoms. In the second O2- site, O2- is bonded to four equivalent Zr4+ atoms to form a mixture of corner and edge-sharing OZr4 tetrahedra.
ZrO2 is Baddeleyite-like structured and crystallizes in the orthorhombic Pca2_1 space group. The structure is three-dimensional. Zr4+ is bonded to seven O2- atoms to form a mixture of distorted edge and corner-sharing ZrO7 pentagonal bipyramids. There are a spread of Zr–O bond distances ranging from 2.06–2.30 Å. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded to four equivalent Zr4+ atoms to form a mixture of edge and corner-sharing OZr4 tetrahedra. In the second O2- site, O2- is bonded in a trigonal planar geometry to three equivalent Zr4+ atoms.
ZrO2 is beta Vanadium nitride-like structured and crystallizes in the tetragonal I4_1/amd space group. The structure is three-dimensional. Zr4+ is bonded to six equivalent O2- atoms to form a mixture of distorted corner and edge-sharing ZrO6 octahedra. The corner-sharing octahedral tilt angles are 29°. There are four shorter (2.10 Å) and two longer (2.18 Å) Zr–O bond lengths. O2- is bonded in a 3-coordinate geometry to three equivalent Zr4+ atoms.
ZrO2 crystallizes in the orthorhombic Pnma space group. The structure is three-dimensional. Zr4+ is bonded to six equivalent O2- atoms to form a mixture of distorted edge and corner-sharing ZrO6 pentagonal pyramids. There are a spread of Zr–O bond distances ranging from 2.11–2.15 Å. O2- is bonded in a trigonal non-coplanar geometry to three equivalent Zr4+ atoms.
ZrO2 is Baddeleyite-like structured and crystallizes in the orthorhombic Pnma space group. The structure is three-dimensional. Zr4+ is bonded to seven O2- atoms to form a mixture of distorted edge and corner-sharing ZrO7 hexagonal pyramids. There are a spread of Zr–O bond distances ranging from 2.08–2.27 Å. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded to four equivalent Zr4+ atoms to form a mixture of distorted edge and corner-sharing OZr4 tetrahedra. In the second O2- site, O2- is bonded in a trigonal non-coplanar geometry to three equivalent Zr4+ atoms.
ZrO2 is Baddeleyite-like structured and crystallizes in the orthorhombic Pnma space group. The structure is three-dimensional. Zr4+ is bonded in a 7-coordinate geometry to seven O2- atoms. There are a spread of Zr–O bond distances ranging from 2.12–2.30 Å. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded in a trigonal planar geometry to three equivalent Zr4+ atoms. In the second O2- site, O2- is bonded to four equivalent Zr4+ atoms to form a mixture of distorted edge and corner-sharing OZr4 tetrahedra.
ZrO2 crystallizes in the monoclinic C2/m space group. The structure is three-dimensional. there are two inequivalent Zr4+ sites. In the first Zr4+ site, Zr4+ is bonded to six O2- atoms to form a mixture of distorted edge and corner-sharing ZrO6 octahedra. The corner-sharing octahedral tilt angles are 32°. There are a spread of Zr–O bond distances ranging from 2.01–2.30 Å. In the second Zr4+ site, Zr4+ is bonded in a 6-coordinate geometry to six O2- atoms. There are a spread of Zr–O bond distances ranging from 1.95–2.46 Å. There are four inequivalent O2- sites. In the first O2- site, O2- is bonded in a 3-coordinate geometry to three Zr4+ atoms. In the second O2- site, O2- is bonded in a distorted trigonal non-coplanar geometry to three Zr4+ atoms. In the third O2- site, O2- is bonded in a linear geometry to two Zr4+ atoms. In the fourth O2- site, O2- is bonded to four Zr4+ atoms to form a mixture of distorted edge and corner-sharing OZr4 trigonal pyramids.
ZrO2 is Rutile structured and crystallizes in the tetragonal P-42_1m space group. The structure is three-dimensional. Zr4+ is bonded to six equivalent O2- atoms to form a mixture of edge and corner-sharing ZrO6 octahedra. The corner-sharing octahedra tilt angles range from 50–51°. All Zr–O bond lengths are 2.13 Å. O2- is bonded in a distorted trigonal planar geometry to three equivalent Zr4+ atoms.
ZrO2 crystallizes in the triclinic P1 space group. The structure is three-dimensional. there are three inequivalent Zr4+ sites. In the first Zr4+ site, Zr4+ is bonded to six O2- atoms to form a mixture of distorted corner and edge-sharing ZrO6 octahedra. The corner-sharing octahedral tilt angles are 25°. There are a spread of Zr–O bond distances ranging from 2.07–2.19 Å. In the second Zr4+ site, Zr4+ is bonded to six O2- atoms to form a mixture of distorted corner and edge-sharing ZrO6 octahedra. The corner-sharing octahedra tilt angles range from 24–25°. There are a spread of Zr–O bond distances ranging from 2.07–2.19 Å. In the third Zr4+ site, Zr4+ is bonded to six O2- atoms to form a mixture of corner and edge-sharing ZrO6 octahedra. The corner-sharing octahedra tilt angles range from 24–25°. There are two shorter (2.11 Å) and four longer (2.13 Å) Zr–O bond lengths. There are six inequivalent O2- sites. In the first O2- site, O2- is bonded in a trigonal non-coplanar geometry to three Zr4+ atoms. In the second O2- site, O2- is bonded in a distorted T-shaped geometry to three Zr4+ atoms. In the third O2- site, O2- is bonded in a distorted T-shaped geometry to three Zr4+ atoms. In the fourth O2- site, O2- is bonded in a distorted T-shaped geometry to three Zr4+ atoms. In the fifth O2- site, O2- is bonded in a distorted T-shaped geometry to three Zr4+ atoms. In the sixth O2- site, O2- is bonded in a trigonal non-coplanar geometry to three Zr4+ atoms.
ZrO2 is Cotunnite structured and crystallizes in the orthorhombic Pnma space group. The structure is three-dimensional. Zr4+ is bonded in a 9-coordinate geometry to nine O2- atoms. There are a spread of Zr–O bond distances ranging from 2.17–2.62 Å. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded to four equivalent Zr4+ atoms to form a mixture of edge and corner-sharing OZr4 tetrahedra. In the second O2- site, O2- is bonded in a 3-coordinate geometry to five equivalent Zr4+ atoms.
Tellurium (Te) has recently emerged as a promising p-type semiconductor that can be processed at low temperatures, compatible with back end of line CMOS integration. Characterization of tellurium–dielectric interfaces is essential for further device advancements. Here, the interface quality of Te with ZrO2 gate dielectric is studied in a metal-oxide semiconductor capacitor structure. The interface trap density (Dit) is measured as a function of atomic layer deposition (ALD) temperature, without the use of a seed layer. Given the low thermal budget of Te, the ALD temperature is shown to be particularly important. The lowest Dit of 5 × 1012 states/cm2 eV is obtained at a low ALD process temperature of 120 °C. To further assess the impact of Dit on device performance, field-effect transistors (FETs) were fabricated. The subthreshold swing and effective hole mobility of the FETs were analyzed in relation to Dit, emphasizing the importance of a defect-minimized interface for enhancing Te transistor performance.
Direct, atomic-scale visualization of polarization switching in a functional, polycrystalline, binary oxide via in-situ high-resolution transmission electron microscopy (HRTEM) biasing is reported for the first time. Antiferroelectric (AFE) ZrO2 was used as the model system, which is important for commercial DRAMs and as emerging NVMs (through work-function engineering). We observed (1) clear shifting and coalescing of domains within a single grain, and (2) dramatic changes of the atomic arrangements and crystalline phases—both at voltages above the critical voltage measured for AFE switching. Similar synergistic in-situ structural-electrical characterization can pave the way to understand and engineer microscopic mechanisms for retention, fatigue, variability, sub-coercive switching and analog states in ferroelectric and AFE-based memory devices.
A study was made of the comparative life of plasma sprayed ZrO2-Y2O3 thermal barrier coatings on NiCrAlY bond coats on Rene 41 in short (4 min) and long (57 min) thermal cycles to 1040 C in a 0.3 Mach flame. Short cycles greatly reduced the life of the ceramic coating in terms of time at temperature as compared to longer cycles. Appearance of the failed coating indicated compressive failure. Failure occurred at the bond coat-ceramic coat junction. At heating rates greater than 550 kw/sq m, the calculated coating detachment stress was in the range of literature values of coating adhesive/cohesive strength. Methods are discussed for decreasing the effect of high heating rate by avoiding compressive stress.
An analysis has been developed which relates the effects of inelastic behavior of Y2O3 stabilized ZrO2 (YSZ) materials. The results show these materials to be sensitive to small changes in temperature and are supported by measurements of inelastic behavior in disk and bar specimens at temperatures as low as 1010 C (1850 F). At higher thermomechanical loads, the test specimens can deform to strains greater than 1 percent and for bar specimens, with sufficient strength, to remain bonded to the metallic substrate.
The thermal expansion properties of plasma-sprayed ZrO2-8-wt pct Y2O3 coatings, detached from the substrate, have been examined. Coatings were heat-treated in air or in argon. Anisotropic effects in the longitudinal (planar to the substrate surface) and transverse (perpendicular to the substrate surface) directions were measured and related to the coating structure. The thermal expansion coefficient of the coating is discussed in terms of the material's properties, such as the crack network and interlamellar boundary distribution. A precise model for the expansion behavior of coatings still needs attention, since no description of all of the contributing variables exists. A quantitative analysis of thermal properties of coatings will aid in future design and modeling of coating systems.
A set of 12.7 mm diameter stainless steel tubes were coated with ceramic and expanded. The bond cast was 0.08 to 0.13 mm NiCrAlY with 0.38 mm of ZrO2-8Y2O3 ceramic. Upon pressurization, the tube substrate yielded and overstressed the coatings in tension. The coatings cracked (i.e., they failed) but did not come off the tube. These results demonstrate that tensile failure of plasma-sprayed coatings is not catastrophic as is compressive failure, which leads to spallation.