Phase transitions and structures in the rare earth hexafluorides Cs2NaHoF6, Rb2NaHoF6, Cs2KHoF6 and Cs2RbHoF6 at 12 &lt; T &lt; 300 K

Ihringer, J.; Wu, Guoqing; Hoppe, R.; Hewat, A.W.

doi:10.1016/0022-3697(84)90016-7

Cited by 12 publications

(5 citation statements)

References 15 publications

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“…It is fortunate that the corresponding transitions have been reported for Cs 2 NaY 0.9-Ho 0.1 Cl 6 so that an analogous interpretation can be made. An unusual feature in the spectra of HoCl 6 [3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22] was the observation of hot bands to low energy of a group of emission bands and the same phenomenon is observed here and serves to confirm the interpretation. 5 G 4 f 5 I 7 Transition.…”

Section: ' Introductionsupporting

confidence: 79%

“…The system has been chosen for comparison with the spectra, energy levels and analysis of the corresponding chloride. Solid-state nuclear magnetic resonance 16 and X-ray crystallographic studies 17 variously concluded that this crystal is cubic (Fm3m) at temperatures down to 393 mK 16 or 12.5 K, 17 compared with the temperature 150 mK for Cs 2 NaHoCl 6 . 18 From our optical spectroscopic measurements, we do not observe a conclusive deviation from cubic symmetry within our temperature range of measurements down to ∼10 K. This considerably simplifies the energy level analysis since only two CFP are thus required for the 4f 10 crystal field analysis.…”

Section: ' Introductionmentioning

confidence: 99%

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Electronic Spectra and Crystal Field Analysis of Energy Levels of Ho³⁺ in HoF₆³⁻

2011

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The electronic absorption spectra of single crystals of Cs(2)NaHoF(6) have been recorded in the spectral region between 4700 and 42000 cm(-1) at temperatures down to 10 K. The structure in the (5)I(8) → (5)I(J) (J = 7-4), (5)F(J) (J = 5-1), (5)S(2), (5)G(J) (J = 4-6), (3)K(J) (J = 7, 8) transitions has been analyzed and assigned. The emission spectra (5)S(2) → (5)I(J) (J = 6-8) and (5)G(4) → (5)I(J) (J = 5-7), (5)F(5) have also been recorded at 10 K for crystals of Cs(2)NaHoF(6) and partly also for samples of Cs(2)NaHoF(6):Yb(3+). The spectra comprise magnetic dipole zero phonon lines and electric dipole allowed one-phonon vibronic sidebands. From the detailed interpretation of the emission and absorption spectra, aided by a clear understanding of the vibrational behavior of the HoF(6)(3-) moiety and by magnetic dipole intensity calculations, a data set of 59 energy levels spanning 17 multiplet terms was derived. Crystal field calculations were then performed using a 4f(10) basis, as well as including the configuration interaction with a p-electron configuration. The latter calculation, which employed 14 parameters, gave better agreement with experiment and the mean deviation was 13.5 cm(-1). A comparison with the energy level fittings for Cs(2)NaHoCl(6) has been included. The crystal field parameters for the fluoro- and chloro-systems followed empirically predicted ratios.

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Section: ' Introductionsupporting

confidence: 79%

Section: ' Introductionmentioning

confidence: 99%

Electronic Spectra and Crystal Field Analysis of Energy Levels of Ho³⁺ in HoF₆³⁻

2011

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“…A more recent review suggests that at least 350 different elpasolites have been synthesized . In Figure we highlight all the elements of the periodic table which belong to known halide elpasolites. ,− A simple count indicates that 7 elements are found as A-site cations, 8 elements can occupy the B + sites (including ammonium and methylammonium), 34 elements are found as B 3+ cations, and 5 elements can occupy the X sites (including the cyanide CN – ). A straightforward multiplication of these numbers yields a stunning 9520 combinations.…”

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confidence: 99%

“…The triangular color tag specifies the site occupied by the element, according to the legend at the top. The compounds used to generate the table are described in refs and − . Only structures that crystallize in the space group Fm m at room temperature have been considered for this table.…”

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confidence: 99%

Toward Lead-Free Perovskite Solar Cells

2016

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Since the first reports of solar cells with power conversion efficiencies around 10% in 2012, the science and technology of perovskite photovoltaics has been progressing at an unprecedented rate. The current certified record efficiency of 22.1% makes perovskites the first solution-processable technology to outperform multicrystalline and thin-film silicon. For this technology to be deployed on a large scale, the two main challenges that need to be addressed are the material stability and the toxicity of lead. In particular, while lead is allowed in photovoltaic modules, it would be desirable to find alternatives which retain the unique optoelectronic properties of lead halide perovskites. Here we offer our perspective on the most exciting developments in the materials science of new halide perovskites, with an emphasis on alternatives to lead. After surveying recent developments of new perovskites and perovskite-related materials, we highlight the potential of halide double perovskites. This new family of compounds constitutes uncharted territory and may offer a broad materials library for solar energy applications.

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“…It resembles in this respect Rb 2 NaHoF 6 [9] or (TMA) 2 PtF 6 [10]. The contrary rotations observed for NO[NbCl 6 ] Á NbCl 5 are common among perovskite-related structures.…”

Section: Discussionmentioning

confidence: 88%

The crystal structures of K[NbCl₆] · NbCl₅ and NO[NbCl₆] · NbCl₅

Henke¹,

Mayer

2010

Zeitschrift Für Kristallographie - Crystalline Materials

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Nitrosonium / Hexachlorido niobates / Disorder / Twinning / Group-subgroup relations / Bärnighausen trees / Single-crystal structure analysis / X-ray diffraction Abstract. The NbCl 5 adducts of M[NbCl 6 ] Á NbCl 5 with M ¼ K or NO are structurally related via their common supergroup Fmmm. K[NbCl 6 ] Á NbCl 5 crystallizes in the triclinic space group C 1 1 with a ¼ 9.898 (1) (1) and Z ¼ 4 at room temperature. For the monoclinic nitrosonium compound with space group C2/c X-ray diffraction data have been recorded at 173 K giving a ¼ 9.530(1), b ¼ 9.412(1), c ¼ 33.38(1) A, b = 92.68(1) and Z ¼ 8. Layers of NbCl 5 dimers alternate with cation-centred double layers of the NbCl 6 À ions, oriented parallel to the a-b plane. Compared to the cubic perovskite SrTiO 3 , the NbCl 6 À 'octahedra' of the K þ salt are uniformly rotated by 5 around the stacking axis. On the contrary, the NO þ salt shows 'antiferrorotative' ordering by AE12 in alternate layers. Crystal symmetry and twinning laws reflect the structural differences, but the similarity between both structures prevails.

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Phase transitions and structures in the rare earth hexafluorides Cs2NaHoF6, Rb2NaHoF6, Cs2KHoF6 and Cs2RbHoF6 at 12 < T < 300 K

Cited by 12 publications

References 15 publications

Electronic Spectra and Crystal Field Analysis of Energy Levels of Ho³⁺ in HoF₆³⁻

Electronic Spectra and Crystal Field Analysis of Energy Levels of Ho³⁺ in HoF₆³⁻

Toward Lead-Free Perovskite Solar Cells

The crystal structures of K[NbCl₆] · NbCl₅ and NO[NbCl₆] · NbCl₅

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Phase transitions and structures in the rare earth hexafluorides Cs2NaHoF6, Rb2NaHoF6, Cs2KHoF6 and Cs2RbHoF6 at 12 < T < 300 K

Cited by 12 publications

References 15 publications

Electronic Spectra and Crystal Field Analysis of Energy Levels of Ho3+ in HoF63−

Electronic Spectra and Crystal Field Analysis of Energy Levels of Ho3+ in HoF63−

Toward Lead-Free Perovskite Solar Cells

The crystal structures of K[NbCl6] · NbCl5 and NO[NbCl6] · NbCl5

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Electronic Spectra and Crystal Field Analysis of Energy Levels of Ho³⁺ in HoF₆³⁻

Electronic Spectra and Crystal Field Analysis of Energy Levels of Ho³⁺ in HoF₆³⁻

The crystal structures of K[NbCl₆] · NbCl₅ and NO[NbCl₆] · NbCl₅