TiO6 Octahedra Research Articles

Hydronium-Crosslinked Inorganic Hydrogel Comprised of 1D Lepidocrocite Titanate Nanofilaments.

When a few drops of acid (hydrochloric, acrylic, propionic, acetic, or formic) are added to a colloid comprised of 1D lepidocrocite titanate nanofilaments (1DLs)-2 × 2 TiO6 octahedra in cross-section-a hydrogel forms, in many cases, within seconds. The 1DL synthesis process requires the reaction between titanium diboride with tetramethylammonium (TMA+), hydroxide. Using quantitative nuclear magnetic resonance (qNMR), thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC), the mass percent of TMA+ after synthesis is determined to be ≈ 13.1±0.1%. The TMA+ is completely removed from the gels after 2 water soak cycles, resulting in the first completely inorganic, TiO2-based hydrogels. Ion exchanging the TMA+ with hydronium results in gels with relatively strong hydrogen bonds. The hydrogels' compression strengths increased linearly with 1DL colloid concentration. At a 1DL concentration of 45gL-1, the compressive strength, at 80% deformation when acrylic acid is used, is ≈325kPa. The strengths are ≈ 50% greater after the TMA+ is removed. The removal of all residual organic components in the hydrogels, including TMA+, is confirmed by qNMR, Fourier-transformed infrared spectroscopy (FTIR), and TGA/DSC. The 1DL phase is retained after gelation, TMA+ removal, and 80% compression.

Synergistic contributions of the poling field-induced changes in local structure on the piezoelectric properties of modified BaTiO3 system

Abstract Local structural heterogeneity is a key factor in improving the piezoelectric properties of non-centrosymmetric piezoelectric systems. This work investigates electric field-induced structural and microstructural changes at localized and average scales to elucidate the structure-property correlations that enhance piezoelectric performance in Sn-doped BaTiO3 systems exhibiting coexisting phase boundaries. Despite showing field-induced structural phase transformation, the sample displays variations in piezocoefficient values with the nature of phase boundary compositions. Raman spectroscopy measurements reveal that the TiO6/SnO6 octahedra near the tetragonal-orthorhombic phase boundary exhibit significantly greater poling field-induced structural heterogeneities in local structure compared to those near the orthorhombic-cubic phase boundary. X-ray absorption spectroscopic results on Ti and Sn K-edge in unpoled and poled samples reveal that the dipolar contribution responsible for the piezoelectricity originates from field-induced distortion associated with both TiO6 and SnO6 octahedra. Near the vicinity of the tetragonal-orthorhombic phase boundary, both the TiO6 and SnO6 contributions are cumulative and exhibit better piezoelectricity. On the other hand, at the orthorhombic-cubic phase boundary, the dipolar contributions from these octahedra are counterintuitive, resulting in a reduction of piezoelectricity. These results could provide a pathway to design materials with an enhanced piezoelectric response by considering various phase boundary aspects before applying a poling field prior to making them piezoactive.

Structural, electrical, leakage current, and magnetic characteristics of double perovskite Nd2NiTiO6

AbstractThis study investigates the structural, electrical, leakage current, and magnetic characteristics of the double perovskite material Nd2NiTiO6 synthesized through the sol–gel citrate auto‐ignition method. The Rietveld refinement of the X‐ray diffraction patterns confirmed a monoclinic symmetry (space group P21/n) with an ordered arrangement of alternate NiO6 and TiO6 octahedra. Impedance spectroscopic analysis exhibited the material's non–Debye‐type relaxation mechanism and semi‐conductive nature. AC conduction analysis revealed that the conduction of charge carriers occurs via the nonoverlapping small polaron hopping mechanism, consistent with Mott's variable range hopping model. Temperature‐ and frequency‐dependent dielectric measurements were interpreted using the Maxwell–Wagner interfacial polarization model. The analysis of thermal‐ and field‐dependent leakage currents established that conduction is ohmic, which the Schottky barrier model explains. Studies on magnetization ruled out the presence of magnetic ordering connected to indirect interaction between Ni2+ ions via Ti4+ ions and the rare‐earth cation (Nd3+) moment.

High pressure ferroelectric-like semi-metallic state in Eu-doped BaTiO3.

We have conducted a detailed high-pressure (HP) investigation on Eu-doped BaTiO3 using angle-resolved x-ray diffraction, Raman spectroscopy, and dielectric permittivity measurements. The x-ray diffraction data analysis shows a pressure-induced structural phase transition from the ambient tetragonal to the mixed cubic and tetragonal phases above 1.4GPa. The tetragonality of the sample due to the internal deformation of the TiO6 octahedra caused by the charge difference from Eu doping cannot be lifted by pressure. Softening, weakening, and disappearance of low-frequency Raman modes indicate ferroelectric tetragonal to the paraelectric cubic phase transition. However, the pressure-induced increase in the intensity of [E(LO), A1(LO)] and the octahedral breathing modes indicate that the local structural inhomogeneity remains in the crystal and is responsible for spontaneous polarization in the sample. The low-frequency electronic scattering response suggests pressure-induced carrier delocalization, leading to a semi-metallic state in the system. Our HP dielectric constant data can be explained by the presence of pressure-induced localized clusters of microscopic ferroelectric ordering. Our results suggest that the HP phase coexistence leads to a ferroelectric-like semi-metallic state in Eu-doped BaTiO3 under extreme quantum limits.

High thermoelectric performance of n–type SrTiO3 by Dy and Nb co–doping

The effects of Dy/Nb co–doping on the structural and thermoelectric properties of Sr1−xDyxTi1−yNbyO3−δ (0 ≤ x, y ≤ 0.10) are systematically investigated. Single–doped Sr0.95Dy0.05TiO3−δ and SrTi0.95Nb0.05O3−δ consist of tetragonal (I4/mcm space group) and cubic (Pm3¯m space group) perovskite phases. On the other hand, Dy/Nb co–doped SrTiO3, Sr1−xDyxTi1−yNbyO3−δ, has a tetragonal perovskite phase (I4/mcm space group) since the Dy/Nb co–doping induces a distortion of the TiO6 octahedra and lowers the crystal symmetry. The co–doping effectively increases the electrical conductivity and reduces the thermal conductivity, thus noticeably enhancing the dimensionless figure–of–merit (ZT). The highest ZT value (0.24) is achieved for Sr0.95Dy0.05Ti0.95Nb0.05O3−δ at 600 °C. This ZT value is 41 % and 50 % larger than those of single–doped Sr0.95Dy0.05TiO3−δ (0.17) and SrTi0.95Nb0.05O3−δ (0.16), respectively, at 600 °C.

The structural mechanisms of pressure-induced phase transitions in the Carpy-Galy phase layered perovskites

In layered perovskites with the Carpy-Galy structural type, similar structural phase transitions occur under high pressure. These structural changes, which are crucial for the pressure-induced phase transition in layered perovskite, were analyzed based on experimental X-ray diffraction data. The tilting of the Ti-O6 octahedra and the distortion of the arrangement of rare-earth atoms were studied in detail. Changes in these structural features in layered perovskite serve as common indicators of the phase transition to the monoclinic phase that occurs under high pressure application.

A study on the improvement of ion conductivity of lithium aluminum titanium phosphate-based solid-state electrolyte by the addition of divalent cations

AbstractNa like super ionic conductors (NASICON)-structure Li1.3Al0.3Ti1.7(PO4)3 solid electrolyte have attracted attention as high ion conductivity and chemical stability. The M1–M2 voids between the TiO6 octahedra and PO4 tetrahedra in a Li1.3Al0.3Ti1.7(PO4)3-based solid electrolyte is a major path for lithium-ion conduction, and it can be widened to increase lithium-ion conductivity by doping. In this study, divalent ions are doped into the Li1.3Al0.3Ti1.7(PO4)3-based electrolyte and widened ion-conduction path and improved ion conductivity. Making doped Li1.3Al0.3Ti1.7(PO4)3 samples starts with melting, then transformed into glass, pulverized, and then subjected to uniaxial compression molding and sintering, after which they are analyzed by scanning electron microscopy (SEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS), and their impedance resistances were measured. The LiTi2(PO4)3 is generated by thermal treatment and crystallized to form an electrolyte whose lattice parameter values depend on the dopant ion and its content, with each divalent ion distorting the lattice and the M1–M2 bottleneck structure differently. Only Mg2+ doping led to a structural change that increases Li-ion conductivity to 1.55 × 10−3 S/cm at 5 mol% of magnesium ion, with the observed threefold increase in conductivity compared to the 4.73 × 10−4 S/cm ion conductivity of LATP ascribable to a widening of the ion-conduction path. Overall, doping an LATP-based solid electrolyte with an appropriate divalent cation is a promising way of improving performance in a manner that has various applications.

Thin-shelled hollow mesoporous TiO2 spheres with less tortuosity as fast-charging anode

TiO2 is a stable and abundantly available material that is a promising alternative to graphite anodes. However, compact stacking of TiO6 octahedra induces repulsion between the inserted Li ions, reducing rate performance and achievable capacity. Herein, we propose mesoporous hollow TiO2 spheres composed of nanosized anatase to mitigate these issues. The hollow structure allows for ion transport both inward and outward. The empty-core material is obtained by depositing sub-20 nm TiO2 particles synthesized through the sol–gel process onto a carbon nanosphere support, followed by scaffold elimination. Thin TiO2 shells facilitate ion migration via a reduced tortuosity with minimizing isolated pore formation, allowing DLi+ of 3.22 × 10−11 cm2 s−1 to be attained, which is 40 times higher than that of bulk-type TiO2. The facile Li-ion transport enables the insertion of 0.66 mol Li ions per mol of TiO2 at 0.5C and 67 % rate performance (10C vs. 0.5C). The designed hollow TiO2 exhibits stable capacity retention of 85.9 % for 1000 cycles at a fast charging rate of 20C. A full cell with a LiFePO4 cathode exhibits 60 % rate capability (2000 vs. 50 mA g−1). Thin mesoporous hollow TiO2 facilitates the Li-ion transport and enable fast charging, confirming the potential of this anode for fast-charging applications.

Study on the Structure, Morphology, Dielectric, and Piezoelectric Properties of Large-Grain (Ba0.85Sr0.15)1-x Pb x TiO3 Ceramic System for 0.02 ≤ x ≤ 0.08.

Barium strontium lead titanate ((Ba0.85Sr0.15)1-x Pb x TiO3), along with various compositions (x(mol %) = 0, 2, 4, and 8), was synthesized through the conventional sol-gel reaction method. Following this, the resultant powders underwent a carefully controlled calcination process at 1000 °C for a period of 4 h. The examination of the crystalline phase of the calcined ceramics was conducted at room temperature using X-ray diffraction. Rietveld refinement of the XRD data, performed using FullProf, revealed that the samples exhibited a tetragonal structure within the space group P4mm. The impact of Pb doping on the lattice structure of BaSr1-x TiO3 was explored by analyzing the charge density distribution. The FTIR analysis unveiled a distinct absorptive band within the 450-600 cm-1 range, indicative of the stretching and bending vibrations associated with TiO6 octahedra. Notably, sintering the material at 1150 °C for 4 h resulted in improved densification, as observed in scanning electron microscopy images showcasing a nearly uniform distribution of densely packed grains. Through the utilization of Williamson-Hall plots derived from XRD data, the average particle diameter was estimated to fall within the range of 131.87-141 nm, with an associated uncertainty ranging from 5 to 10%. Additionally, the dielectric characteristics unveiled the presence of a negative dielectric constant (εr) spanning the frequency range from 1 kHz to 2 MHz. The (Ba0.85Sr0.15)1-x Pb x TiO3 ceramic displayed a widespread occurrence of negative permittivity, emphasizing the influence of dielectric resonance. The investigation revealed that the sintered ceramic with the formula (Ba0.85Sr0.15)1-x Pb x TiO3 exhibited exceptional piezoelectric properties, achieving the highest piezoelectric constant (d33 = 137 pC/N) and electromechanical coupling factor (k p = 0.49).

Nb/Mn co‐doping enhances the pyroelectric properties of Na0.5Bi4.5Ti4O15 ceramics for infrared detection

AbstractThe pyroelectric effect has wide applications in various fields, such as infrared imaging, detection, alarms, and the expanding field of smart homes. The rapid advancement of smart systems, focusing on miniaturization and integration, requires pyroelectric infrared detectors with high pyroelectric coefficients and Curie temperatures to meet the requirements of integrated processes. However, the Curie temperature of commercial lead zirconate titanate is limited to <230°C, urgently looking for a breakthrough. Here, we explore pyroelectricity in Na0.5Bi4.5Ti4O15 (NBT) ceramics, characterized by a high Curie temperature (∼660°C). We systematically examined the crystal structure modifications and defect dipole effects of the Nb/Mn‐co‐doped NBT. The lattice expansion, distortion of the TiO6 octahedra, and structural transformation tendency from the orthorhombic to tetragonal phase facilitate dipole movements with increasing temperature. Furthermore, the Mn and Nb elements result in the formation of MnTi“–VO·· and NbTi·–MnTi” –NbTi· defect dipoles, inducing additional polarization changes in response to temperature variations. Finally, a significantly improved pyroelectric coefficient of 110 µC m2 K–1 and remarkable temperature stability from 25°C to 300°C is achieved in NBTM‐5Nb ceramics. This co‐doping strategy for enhancing pyroelectric performance can be expanded to other systems and substantially contribute to advancing high‐performance materials for infrared detection.

A search for pressure-induced phase transition in the layered perovskite-like Pr2Ti2O7

In our study, we present comprehensive findings on the structural properties of Pr2Ti2O7 across a broad pressure range of 0–30 GPa. Neutron diffraction experiments, conducted under ambient conditions, offer crucial structural insights into the initial monoclinic phase with the P21 space group. As pressure increased, a significant phase transition to the monoclinic P21/m phase occurred at 13.8 GPa. Structural data analysis from X-ray diffraction highlights the essence of this transition, identifying it as the tilting of Ti-O6 octahedra. High-pressure Raman spectroscopy data unequivocally confirms the phase transition, detecting anomalies in the baric dependencies of some vibration modes of Pr2Ti2O7 and the emergence of new modes in the Raman spectra within the pressure region associated with the phase transition. The analysis of these novel vibration modes points to alterations in the Ti-O6 octahedra, emphasizing the pivotal role played by Ti4+ and O2- ions in the mechanism of the pressure-driven phase transition.

Photocatalytic activity of BaTi5O11 nanocrystals synthesized by hydrothermal method

[Formula: see text] nanocrystals were synthesized by a hydrothermal method, and their photocatalytic performance was investigated by degradation of methylene blue (MB) under UV-light irradiation. About 82% MB was photodegraded after 30 min irradiation, which indicated that the [Formula: see text] nanocrystals had good photocatalytic performance due to the distorted [Formula: see text] octahedra in the monoclinic [Formula: see text] crystal structure and nano-size [Formula: see text] particles. It indicated that the [Formula: see text] nanocrystals were promising candidates as UV-light photocatalysts.

Structural and Photoluminescence Properties of Ca2+-Substituted Self-Activated Photoluminescence Material of Na2TiSiO5

The effects of Ca2+ substitution on the structural and optical properties of Na2TiSiO5 were studied. It was expected that the Ca2+ ions would replace Na+ ions and change the coordination of Ti4+-O2- as a luminescence center. Na2(1‑x)CaxTiSiO5 (x = 0.00, 0.50, 1.00) samples were synthesized using the solid-state method, and their structural properties, the local Ti4+-O2- coordination, the absorption spectra, and the photoluminescence properties were studied. The electronic structure of Na2(1-x)CaxTiSiO5 with x = 0.00 and 1.00 was also calculated using the Full Potential Linear Augmented Plane Wave (FP-LAPW) method to explain some of the observed properties. The Ca2+ substitution resulted in a phase transformation from an orthorhombic to a monoclinic structure. The number of TiO6 octahedra increased with the increase of Ca2+ and correlated with the decrease of PL emission intensity of the Na2(1‑x)CaxTiSiO5 samples. The Ti-3d bands in the CaTiSiO5 were more dispersive than in the Na2TiSiO5 and were responsible for the PL emission intensity reduction.

High-performance piezoelectric energy harvesting in amorphous perovskite thin films deposited directly on a plastic substrate

Most reported thin-film piezoelectric energy harvesters have been based on cantilever-type crystalline ferroelectric oxide thin films deposited on rigid substrates, which utilize vibrational input sources. Herein, we introduce flexible amorphous thin-film energy harvesters based on perovskite CaCu3Ti4O12 (CCTO) thin films on a plastic substrate for highly competitive electromechanical energy harvesting. The room-temperature sputtering of CCTO thin films enable the use of plastic substrates to secure reliable flexibility, which has not been available thus far. Surprisingly, the resultant amorphous nature of the films results in an output voltage and power density of ~38.7 V and ~2.8 × 106 μW cm−3, respectively, which break the previously reported record for typical polycrystalline ferroelectric oxide thin-film cantilevers. The origin of this excellent electromechanical energy conversion is systematically explored as being related to the localized permanent dipoles of TiO6 octahedra and lowered dielectric constant in the amorphous state, depending on the stoichiometry and defect states. This is the leading example of a high-performance flexible piezoelectric energy harvester based on perovskite oxides not requiring a complex process for transferring films onto a plastic substrate.

Simultaneously enhanced of energy storage and energy harvesting performances of [(Bi0.5Na0.5)TiO3–BaTiO3] ceramics by addition of SrTiO3

As is well known, relaxor dielectrics are characterized by high energy storage efficiency (η), while high recoverable energy storage density (Wrec) can be achieved by anti-ferroelectric ceramics. Herein, our approach is to find relaxor- anti-ferroelectric coexistence phases of (Bi0.5Na0.5)TiO3- BaTiO3 ceramics for achieving high performance in energy storage and energy harvesting as well. Therefore, [(0.9-x) ( Bi0.5Na0.5)TiO3-xSrTiO3-0.1BaTiO3] (abbreviation (0.9-x) NBT-0.1BT-xST) (0.0 ≤ x ≤ 0.4) were synthesized via the solid-state reaction route in air. The tolerance factor (τ) increased from 0.9901 to 0.9998 when ST-content increased from 0.0 to 0.4, indicating an increase in crystal lattice symmetry. The FT-IR de-convolution vibration modes shown in the TiO6 octahedra exhibit two peaks at ∼550 and 650 cm−1, which indicate present coexistence phases of the crystal structure. Ferroelectric to relaxor phase crossover has been detected by the addition of ST with the present anti-ferroelectric phase in particular dopant ST = 0.2. The increasing into the diffused phase transition (γ) is signified by enhancement of the relaxor degree of NBT-BT at high content of ST. The rapidly suppressed remnant polarization (Pr) at high content of ST is due to substitute iso-valence (Sr2+) by tri-valence (Bi3+) and mono-valence (Na1+). Ultrahigh Wrec = 1.13 J/ cm3 with excellent η = 92.62% were obtained at ST = 0.3 at low electric field (E = 110 kV cm−1). A remarkable response of the strain with a high converse piezoelectric coefficient ( d33* = 390.47 pm V−1) at ST = 0.2 was obtained due to decreasing the non-revisable 180° domain switching. Based on the obtained results, the addition of ST to NBT-BT ceramics can provide a head start in the implementation of ceramic capacitors for potential effective into energy harvesting and energy storage applications.

Structure, dielectric, and energy storage properties of perovskite CaTiO3 ceramic synthesized using the natural calcium from Pensi shell (Corbicula moltkiana) waste

Recently, dielectric capacitors have attracted immense interest as energy storage materials. In this work, we prepare the dielectric material CaTiO3 by the molten-salt method, utilizing Pensi shell waste as a natural calcium source, aligning with principles of green chemistry. Pensi shell contains 53.1 % calcium oxide, as revealed by TGA analysis, suggesting its potential use as a natural precursor in CaTiO3 synthesis. The phase formation, structure, and electrical properties of the resulting CaTiO3 phase are investigated. XRD data revealed the formation of single-phase CaTiO3 and a distortion of the TiO6 octahedra, accompanied by displacement of the A-site cations resulting in an orthorhombic Pbnm structure. CaTiO3 exhibits good linear dielectric characteristics with an energy storage efficiency of 84.8 %.

Tailoring the crystal distortion and dielectric properties of 0.7CaTiO3-0.3NdAlO3 microwave ceramics by La, Sm and Eu doping into A-site Nd

The TiO6 octahedra titling and rotation play an important role in affecting the microwave properties of 0.7CaTiO3-0.3NdAlO3 microwave ceramics by A-site La, Sm and Eu doping. The oxygen octahedra of Sm-doped 0.7CaTiO3-0.3NdAlO3 ceramics exhibit antiphase tilting, while both in-phase and antiphase tilting coexist in the 0.7CaTiO3-0.3EuAlO3 ceramics. There is an undeniable correlation between the crystal distortion and the tolerance factor t. As the tolerance factor t continues to increase, the crystal structure of A-site doped CTNA ceramics changes from both in-phase tilting and antiphase tilting to untilted structure and the TiO6 octahedra exhibits an inclination to tilt around c axis. The weakening bending vibration of the Ti–O(2)-Ti bond results in the increase of the polarization and the damping coefficient of lattice vibration. The dielectric constant (εr) rises to 48 from 43 and Q × f values decrease to 36,000 GHz from 44,800 GHz (measured at 6 GHz). These findings could be used to guide the tailoring of the crystal distortion and microwave dielectric properties of technologically important perovskite 0.7CaTiO3-0.3NdAlO3 based ceramics.

Negative Lattice Expansion in an O3‐Type Transition‐Metal Oxide Cathode for Highly Stable Sodium‐Ion Batteries

AbstractThe sodium extraction/insertion in layered transition‐metal oxide (TMO) cathode materials are typically accompanied by slab sliding and lattice changes, leading to microstructure destruction and capacity decay. Herein, negative lattice expansion is observed in an O3 type Ni‐based layered cathode of Na0.9Ni0.32Zn0.08Fe0.1Mn0.3Ti0.2O2 upon Na+ extraction. It is attributed to the weak Zn2+−O2− orbital hybridization and increased electron density of the surrounding oxygen for reinforced interlayer O−O repulsive force. This enables gliding of TMO slabs for the intergrowth phase transition of P3→OP2 to alleviate lattice strain with moderate lattice shrinkage, which exhibits general interslab spacings and volume changes as low as 2.4 % and 1.9 %, respectively. The strong Ti−O bonds accommodate the internal distortion of TMO6 octahedra due to the flexibility of TiO6 octahedra during cycling. These endow a high specific capacity of 144.9 mAh g−1 and excellent cycling performance of pouch‐type sodium‐ion batteries with 93 % capacity retention after 3600 cycles.

Negative Lattice Expansion in an O3-Type Transition-Metal Oxide Cathode for Highly Stable Sodium-Ion Batteries.

The sodium extraction/insertion in layered transition-metal oxide (TMO) cathode materials are typically accompanied by slab sliding and lattice changes, leading to microstructure destruction and capacity decay. Herein, negative lattice expansion is observed in an O3 type Ni-based layered cathode of Na0.9 Ni0.32 Zn0.08 Fe0.1 Mn0.3 Ti0.2 O2 upon Na+ extraction. It is attributed to the weak Zn2+ -O2- orbital hybridization and increased electron density of the surrounding oxygen for reinforced interlayer O-O repulsive force. This enables gliding of TMO slabs for the intergrowth phase transition of P3→OP2 to alleviate lattice strain with moderate lattice shrinkage, which exhibits general interslab spacings and volume changes as low as 2.4 % and 1.9 %, respectively. The strong Ti-O bonds accommodate the internal distortion of TMO6 octahedra due to the flexibility of TiO6 octahedra during cycling. These endow a high specific capacity of 144.9 mAh g-1 and excellent cycling performance of pouch-type sodium-ion batteries with 93 % capacity retention after 3600 cycles.

Effects of Zr4+ and Hf4+ substitution on the structure and dielectric response of Ba4Sm9.33Ti18O54 ceramics

Microwave dielectric ceramics with high relative permittivity (εr) are commonly used for the miniaturation of microwave devices. The dielectric loss mechanism of microwave dielectric ceramics, as well as the property modification, has been a concerned topic among scholars. Herein, the lattice structure, defects, and broadband dielectric response of Zr4+ and Hf4+ substituted Ba4Sm9.33Ti18O54 (BST) ceramics are systematically examined. The negative temperature coefficient of resonant frequency (τf) of BST ceramics can be tuned to near zero via ion substitution, owing to the Sm2Ti2O7 second phase with a large positive τf. Optimal microwave dielectric properties of εr = 81.3, Q × f = 10,800 GHz, and τf = −4.6 ppm/°C are achieved. The lattice vibration behavior and defect concentration are analyzed by Raman spectra and thermally stimulated depolarization currents (TSDC), respectively. The increasing volume of the unit cell and TiO6 octahedra, which is because of the large-radius substitution ions, leads to an increase in lattice vibration damping factor and the generation of more oxygen vacancies (VO∙∙). Therefore, the dielectric losses in the microwave and terahertz (THz) bands increase after substitution. Meanwhile, the low-frequency dielectric losses at high temperatures also increase due to the weak restraint of carriers by the lattice. The broadband loss mechanism of Zr4+ and Hf4+ substituted BST ceramics related to lattice vibration and defects might be referenced for developing low-loss dielectric ceramics.