Introduction As a core energy storage device of high energy pulse power supply, dielectric energy storage materials have the characteristics of high-power density, fast charging and discharging rate, good temperature stability, and intense aging resistance. They are widely used in power and electronic systems such as hybrid electric vehicles, oil exploration, directional weapons, etc., especially in high energy pulse power technology, having irreplaceable application prospects. With the rapid development of pulse power electronic systems, higher requirements are placed on the energy storage density, discharge current and time of dielectric capacitors in pulse power systems. These advanced devices are used in scenarios such as 100 kA current or 100 kV high voltage. This becomes some challenges for the energy storage density of dielectric capacitors. In addition, a problem of low energy storage density of dielectric capacitors also makes the pulse power system too large and cumbersome to meet the requirements of practical equipment platforms for small and lightweight high-tech weapons. Dielectric energy storage materials are key materials for pulse power devices, but their low energy storage density severely limits the miniaturization of dielectric capacitors. Further improving the breakdown field strength and increasing the dielectric constant to obtain high energy storage density dielectric materials remain a major challenge. It is necessary to develop new technologies that can improve the energy density of dielectric capacitors or explore new material systems with a high energy storage density. Doping rare-earth oxides into glass ceramics can enhance their dielectric and energy storage properties. The rare-earth element La3+ has a unique 4f electron layer structure, large ion radius and a high coordination number. Incorporating La3+ into the glass ceramics has an impact on their phase structure, dielectric properties, and energy storage performance. It is thus expected that the energy storage performance of glass ceramics can be improved via doping the rare-earth element La3+.Methods Strontium barium niobate glass ceramics doped with different mole fractions of La3+ were prepared via high-temperature melting and subsequent temperature-controlled crystallization. The strontium barium niobate glass ceramic had a composition of 20SrO-20BaO-20Nb2O5-33.5SiO2-5Al2O3-1.5B2O3. Different mole fractions (i.e., 0.5%, 1.0% and 1.5%, in mole) of La3+ elements were doped into the galss ceramics. The raw materials were weighed according to the stoichiometric ratio and evenly mixed/ground in a ball mill. The mixed raw materials were sintered in a high-temperature glass furnace at 1 550 ℃ for 2.5 h. The molten material was quickly poured into a preheated metal mold to create a bulk glass. The glass was then held at 650 ℃ for 3 h to remove any remaining stresses. The transparent glass was cut into flakes with the sizes of 1.5 mm×6.0 mm×6.0 mm and heated to 1 100 ℃ for 3 h. Finally, strontium barium niobate glass ceramics with varying mole fractions of La3+ doping were prepared.The phase structure and content of La3+ doped strontium barium niobate-based glass ceramics were analyzed by a model D8 Advanced X-ray diffractometer. The crystal size and microstructure of glass ceramics were determined by a model XL30-FEG scanning electron microscope. The dielectric constant and dielectric loss of glass ceramics at different temperatures were measured by a model E4980A LCR meter. The breakdown strength of glass ceramics was evaluated by a model ET2671B breakdown resistance tester. The P-E polarization curve of glass ceramics was tested by a model Premier-II ferroelectric tester.Results and discussion The impact of doping mole fractions of La3+ on the phase structure, microstructure, and dielectric constant, loss, breakdown field strength, and energy storage performance of strontium barium niobate glass ceramics was investigated via experiments and theoretical simulation to reveal the mechanism of enhancing the energy storage performance of strontium barium niobate glass ceramics. The results show that La3+ doping can improve the crystallinity and the content of tungsten bronze structure Ba0.5Sr0.5Nb2O6 of the glass ceramics, thereby increasing the dielectric constant of strontium barium niobate glass-ceramics. At doping mole fractions of 0.5%, 1.0%, and 1.5% for La3+, the room-temperature dielectric constants of strontium barium niobate glass ceramics are 76.3, 96.3, and 88.1, respectively. These values are all greater than the dielectric constant of undoped strontium barium niobate glass ceramics (i.e., 65.7). La3+ doped strontium barium niobate glass ceramics have a superior temperature stability and a low loss. The optimum La3+ doping mole fraction can improve the microstructure and reduce the interface activation energy of glass ceramics, thus enhancing the breakdown strength of glass ceramics. When the doping mole fraction of La3+ is 1.0%, the breakdown strength of the glass ceramics reaches 1 458 kV/cm, and the dielectric constant is 96.3. The maximum energy storage density reaches 9.36 J/cm3, which is 2.25 times greater than that of undoped strontium barium niobate glass ceramics.Conclusions In the controlled doping amount of La3+ of glass ceramics, the phases and microstructure of glass ceramics could be effectively controlled. This improved the dielectric properties and breakdown strength of the glass ceramics. The increase in energy storage density of strontium barium niobate glass ceramic with an appropriate doping amount of La3+ was attributed to the increase in crystallinity and decrease in interfacial activation energy of the glass ceramics. This study could provide a reference for the development of high energy storage density glass-ceramics.