Mixed anion control of enhanced negative thermal expansion in the oxysulfide of PbTiO.

The rare physical property of negative thermal expansion (NTE) is intriguing because materials with a large NTE over a wide temperature range can serve as high-performance thermal expansion compensators. However, the applications of NTE are hindered by the fact that most of the available NTE materials show small magnitudes of NTE, and/or NTE occurs only in a narrow temperature range. Herein, for the first time, we investigated the effect of anion substitution instead of general Pb/Ti-site substitutions on the thermal expansion properties of a typical ferroelectric NTE material, PbTiO.

Second Harmonic Generation in β-KTeWO: An Acentric Crystal Designed from Centric Phase via Pressure Modulation.

The latent value of nonlinear optical (NLO) crystals applied in solid-state laser equipment necessitates the development of applicable strategies for constructing noncentrosymmetric (NCS) crystals. By modulating the synthetic temperature and pressure to achieve the rearrangement of [TeO] groups, a new NCS tellurium tungstate, β-KTeWO (β-KTW), with a strong second harmonic generation (SHG) response was synthesized based on its centrosymmetric polymorphic phase α-KTeWO (α-KTW). Computational calculation reveals that the large SHG response of β-KTW (15 × KHPO@1064 and 1.

NaMoO(IO)(HO): water molecule introduction induces strong second harmonic generation response, widened band gap and large anisotropy.

Exploring feasible tactics to induce the formation of non-centrosymmetric (NCS) structures, especially from centrosymmetric (CS) structures, is essential for the development of nonlinear optical crystals with more potential. An NCS alkali metal-containing molybdenum iodate hydrate, namely, NaMoO(IO)(HO), was designed based on the CS matrix NaMoO(IO) introducing a water molecule into the structure. The introduction of one crystalline water molecule results in the rearrangement of Λ-shaped -[MoO(IO)] units, and the proper array of the -[MoO(IO)] units in NaMoO(IO)(HO) results in its strong SHG response of 4.

Photoluminescence and Nonlinear Optical Properties of Two Terpyridine-Based Hybrid Zn/Cd Halides.

Hybrid metal halides (HMHs) with low-dimensional structures have attracted increasing attention due to their striking optical properties. Herein, two new zero-dimensional HMHs have been fabricated by CdCl/ZnCl and 4'-(4-pyridyl-phenyl)-2,2':6',2″-terpyridine (), including (TpyH)[CdCl][Cl] () and (TpyH)[ZnCl][Cl] (). Their structures are consisted of a [TpyH] organic cation, an inorganic [ZnCl] or [CdCl] tetrahedron, and one isolated Cl anion.

RE(OH)NO (RE = Tb, Dy, Ho, and Er): Synthesis and Nonlinear Optical Properties of Water-Resistant Lanthanide Hydroxide Nitrates.

A series of lanthanide-containing water-resistant nitrates, namely RE(OH)NO (RE = Tb(), Dy(), Ho(), and Er()), was obtained through the hydrothermal process. As possible nonlinear optical materials, they feature a layered isomorph composed of an [REO(OH)] polyhedron and an [NO] triangle, and the synergistic arrangement of the [REO(OH)] and [NO] groups in their structures leads to their obvious second-order nonlinear optical effect. Nevertheless, the unique optical absorption caused by the electronic transitions on 4f-4f orbitals of lanthanides results in their second harmonic generation responses of different strengths, with exhibiting 5.