99.999% High-Purity Magnesium Oxide: Breaking the Bottleneck of Core Piezoelectric Materials, Domestic Substitution Is Now Here

From 5G/6G communication filters and medical ultrasonic probes to vehicle-mounted sensors and aircraft vibration monitors, the core of these devices is piezoelectric ceramics or piezoelectric crystals. They convert tiny mechanical vibrations into precise electrical signals, or transform electric fields into mechanical deformation. To ensure sensitive, stable and reliable electromechanical conversion, raw material purity is the fundamental factor determining performance. As an auxiliary material accounting for less than 1% of the total formula, high-purity magnesium oxide is the key to the performance of piezoelectric materials.

Piezoelectric materials feature mutual conversion between force and electricity. They generate voltage under pressure and deform when an electric field is applied. Even the electric spark from a common lighter is produced by piezoelectric ceramics.

From the perspective of industrial chain, the upstream consists of high-purity inorganic salts and production equipment, the midstream is the manufacturing of piezoelectric materials, and the downstream covers consumer electronics, industrial manufacturing, aerospace, automotive, medical devices and other fields. Known as the "industrial vitamin", piezoelectric materials have been widely applied across the high-tech industry.

Medical ultrasonic probes, 5G/6G high-frequency filters, smartphone microphones, vehicle ultrasonic sensors and aircraft vibration testing equipment all rely on piezoelectric materials. A new energy vehicle is equipped with 15 to 20 piezoelectric sensors on average, and the market demand for PMN-PT single crystals used in medical ultrasonic probes keeps growing.

In 5G/6G base stations, piezoelectric ceramics effectively filter signals. The higher the communication frequency, the stricter the requirements for filter precision. As the core component for high-frequency filtering, the stability of piezoelectric materials ensures signals are free from noise interference.

In medical ultrasonic probes, piezoelectric crystals convert acoustic waves into clear images. The imaging resolution depends entirely on the sensitivity and uniformity of piezoelectric materials.

In aircraft engines, piezoelectric sensors monitor subtle abnormal vibrations in real time. Only ultra-pure and stable materials can guarantee zero false alarms and missed detections under high temperature and high rotating speed.

All these demanding application scenarios rely on one essential raw material — high-purity magnesium oxide.

High-Purity Magnesium Oxide: A Minor Ingredient That Determines Piezoelectric Material Performance

Magnesium oxide acts as a critical sintering aid in the production of piezoelectric ceramics. Though not the main component, it is irreplaceable. It can significantly lower the sintering temperature, promote particle diffusion and rearrangement, and form a dense microstructure to improve the density and uniformity of ceramics. It also optimizes dielectric constant and piezoelectric coefficient to enhance electrical properties, and boosts hardness and flexural strength, so as to improve the stability and durability of piezoelectric ceramics under high temperature, high pressure and other harsh conditions.

High-purity magnesium oxide is also an essential dopant for piezoelectric crystals. For example, doping lithium niobate crystals with MgO can greatly reduce the photorefractive effect and raise the optical damage resistance threshold by 1 to 2 orders of magnitude, which meets the core requirements of laser, quantum optics and other cutting-edge applications.

High-purity magnesium oxide can improve the piezoelectric constant and dielectric constant of piezoelectric ceramics. Excessive addition will cause adverse effects and weaken dielectric and piezoelectric performance. Therefore, the purity, dosage, particle size distribution and crystal structure of magnesium oxide for piezoelectric ceramics must be precisely controlled. A tiny dosage can fully activate the potential of piezoelectric materials, on the premise that magnesium oxide is ultra-high purity.

Industrial-grade magnesium oxide (85%~98%) is only used for low-end refractory materials and building materials. Medium and high-grade refined magnesium oxide (99%~99.8%) is applied in catalysts, pharmaceutical excipients and other general industrial fields. For piezoelectric ceramics and crystals with extremely high requirements for signal accuracy, the purity standard rises to over 99.99% (4N), and 99.999% (5N) ultra-high purity is required for high-end applications.

Trace impurities (less than 0.001%) will become noise sources for piezoelectric signals. Impurities such as iron, silicon, sodium and potassium lead to dielectric loss, fluctuation of piezoelectric coefficient and reduced energy conversion efficiency. They also cause lattice defects and micro-stress concentration, resulting in premature cracking and failure of ceramics under long-term vibration. In addition, impurity ions will reduce insulation resistance and cause leakage current of piezoelectric components under high voltage, which directly affects the safety and service life of equipment.

For precision devices such as sensors and filters, even minor batch fluctuations of several ppm will lead to unqualified product consistency and a sharp drop in yield. A 5G base station filter module contains dozens of piezoelectric components, which must maintain nearly identical electrical response to guarantee signal quality.

Impact of Impurities on Piezoelectric Signals

Key Contaminants: Iron (Fe), Silicon (Si), Sodium (Na), Potassium (K)

Clean Signal (High-Purity MgO)

Noisy Signal (Impurity-Contaminated MgO)

Impurity Hazards:

Silicon (Si): Signal Drift & Resonant Frequency Offset

Potassium (K): High-Frequency Signal Jitter

Iron (Fe): Signal Distortion & Amplitude Loss

Sodium (Na): Instability

China boasts the world’s largest and fastest-growing piezoelectric material market, yet it faces a structural dilemma in high-end sectors. Domestic manufacturers are mainly engaged in low-value-added piezoelectric components, while core raw materials for high-end piezoelectric crystals and high-performance piezoelectric ceramics have long relied on imports.

The market of high-purity magnesium oxide faces the same situation. According to industry data, the localization rate of high-purity magnesium oxide is expected to reach 35%-40% in 2025. Nevertheless, the high-end electronic-grade market (≥99.9%) is still monopolized by overseas suppliers. In particular, 99.999% (5N) ultra-high purity magnesium oxide has not achieved large-scale mass production in China for a long time.

Import dependence brings not only high costs but also hidden risks to supply chain security for downstream piezoelectric enterprises. Long lead times, price volatility and changes in trade policies may disrupt the normal operation of production lines.

Against the fierce competition for high-purity materials, Shanghai Sheeny Metal has made a breakthrough. We have taken the lead in realizing large-scale mass production of 99.99% (4N) to 99.999% (5N) ultra-high purity magnesium oxide in China. For our 5N grade products, the content of iron (Fe) is controlled at ≤2ppm, while cobalt (Co), nickel (Ni) and chromium (Cr) are all below 1ppm. The relative standard deviation (RSD) of key indicators across batches is within 5%, and can be as low as 3% for core parameters.

Our products can be directly applied by piezoelectric manufacturers without repeated formula and process adjustment, thoroughly ensuring product consistency and reliability. We provide ultra-pure raw material support for piezoelectric ceramics and crystals, and help domestic high-end materials upgrade from qualified products to premium products.

Piezoelectric ceramics and crystals are essential components of high-end manufacturing. Stable electromechanical conversion with ultra-low noise is the foundation for high-performance equipment to work accurately in harsh environments. In this field, high purity is an uncompromising requirement.

Shanghai Sheeny Metal Materials Co., Ltd. focuses on the R&D and production of ultra-high purity magnesium oxide. Our stable mass production of 99.999% (5N) magnesium oxide has broken foreign technical monopoly. We supply high-purity, high-stability and high-consistency core raw materials for piezoelectric crystals, transparent ceramics, scintillation crystals and other high-end precision fields. We believe that ultra-high purity and stable quality of raw materials are the core driving force for the upgrading of China’s high-end manufacturing industry.