Technology and the built world

Sodium iron phosphate

Sodium iron phosphate, NaFePO₄, is a cathode material for sodium-ion batteries with olivine and maricite phases; the related pyrophosphate NFPP entered 10,000-ton production in 2025.

Sodium layered oxide

A sodium layered oxide is a cathode material for sodium-ion batteries, formula NaxTMO2, with sodium ions between TMO6 slabs and O3, P3, P2, and O2 structural types.

Sodium manganese oxide

Sodium manganese oxide, written NaxMnO2, is a family of compounds serving as cathode materials in sodium-ion batteries, valued because sodium and manganese are abundant and inexpensive.

Sodium metal anode

A sodium metal anode is a battery negative electrode of metallic sodium with 1,166 mAh/g capacity and a low redox potential, central to sodium-metal batteries.

Sodium metal chloride battery

A sodium metal chloride battery, best known as the ZEBRA battery, is a high-temperature rechargeable battery using molten sodium, a ceramic separator, and a metal chloride electrode.

Sodium nickel manganese oxide

Sodium nickel manganese oxide, abbreviated NNMO and chiefly the composition NaNi0.5Mn0.5O2, is a layered oxide cathode material for sodium-ion batteries, first used in a full cell in 2011.

Sodium niobate

Sodium niobate (NaNbO3) is an antiferroelectric perovskite oxide of sodium, niobium, and oxygen, discovered in 1949 and the sodium end member of the KNN lead-free piezoelectric ceramics.

Sodium sulfide solid electrolytes

Sodium sulfide solid electrolytes are inorganic sodium-ion conductors such as Na₃PS₄ and Na₃SbS₄, whose soft, highly polarizable lattices give liquidlike conductivity but suffer moisture sensitivity and narrow electrochemical stability windows.

Sodium superionic conductor electrolytes for all-solid sodium cells

Sodium superionic conductor (NASICON) electrolytes, including the sodium zirconium silicophosphate family, are solid materials used as the ion-transport layer in all-solid-state sodium batteries.

Sodium titanate cathode

Sodium titanate cathode is a term sometimes applied to sodium titanate materials, chiefly layered Na₂Ti₃O₇, used as anodes in sodium-ion batteries at about 0.3 V.

Sodium vanadium fluorophosphate

Sodium vanadium fluorophosphate (Na₃V₂(PO₄)₂F₃, commonly abbreviated NVPF) is a polyanionic cathode material for sodium-ion batteries, first synthesized in 1999 and used in TIAMAT's commercial cells.

Sodium vanadium phosphate

Sodium vanadium phosphate, abbreviated NVP, is a NASICON-family compound used as a cathode material in sodium-ion batteries, with a 3.4 V operating voltage and 117.6 mAh/g theoretical capacity.

Sodium-air battery

A sodium-air battery is a metal-air electrochemical cell that oxidizes a sodium anode and reduces oxygen at the cathode, studied as an inexpensive, high-energy alternative to lithium-ion batteries.

Sodium-cooled fast reactor

A sodium-cooled fast reactor (SFR) is a nuclear reactor that uses liquid sodium coolant and fast neutrons without a moderator, recycling plutonium and other actinides in a closed fuel cycle.

Sodium-ion battery

The sodium-ion battery, also known as the Na-ion battery, is a rechargeable battery that shuttles sodium ions between electrodes, now commercial in China with lower costs than lithium-ion.

Sodium-ion battery anode

The sodium-ion battery anode is the negative electrode of a sodium-ion battery, storing sodium ions during charging; hard carbon is the standard material, with alloying alternatives like antimony and phosphorus.

Sodium-vapor lamp

The Sodium-vapor lamp (sodium lamp) is an arc discharge lamp used for street lighting. Low-pressure types are nearly monochromatic yellow with high efficacy, whereas high-pressure versions offer golden-white color.

Sodium–sulfur battery

The sodium–sulfur battery (NaS battery) is a rechargeable battery with molten sodium and sulfur electrodes separated by a ceramic electrolyte, commercialized by NGK and TEPCO in 2002.

Södra Cell

Södra Cell is the pulp-producing business area of the Swedish forest industry group Södra, with mills at Värö, Mörrum, and Mönsterås, and a significant producer of biofuels and green electricity.

Soekarno–Hatta International Airport

Soekarno–Hatta International Airport, also known as Bandara Internasional Soekarno-Hatta, is Indonesia's main international gateway, located in Tangerang, Banten, near Jakarta and named for Sukarno and Mohammad Hatta.

SOEM

SOEM, or Simple Open EtherCAT Master, is an open-source C library implementing an EtherCAT master for real-time industrial communication, designed for embedded systems and widely used in robotics via ROS.

SOFA (software)

SOFA, short for Simulation Open-Framework Architecture, is an open-source C++ framework for interactive physics simulation based on the Finite Element Method, emphasizing medical simulation and robotics.

Soffit

A soffit is the finished underside of an architectural element such as an eave, arch, beam, or stair, often carrying vents that ventilate the attic.

SoFi soft robotic fish actuation

SoFi soft robotic fish actuation is the hydraulic mechanism by which SoFi, a soft robotic fish built at MIT's CSAIL, swims, pumping water into two silicone tail chambers.

SoFi Stadium

SoFi Stadium is a 70,000-seat stadium in Inglewood, California, opened in 2020 as home to the Los Angeles Rams and Chargers, built at a cost of about $5 billion.

Sofie Surgical Robot

Sofie (Surgeon's Operating Force-feedback Interface Eindhoven) is an experimental surgical robot for minimally invasive surgery developed at Eindhoven University of Technology, offering force feedback and a compact, table-mounted slave robot.

Sofiya Ozerkova

Sofiya Ozerkova, born in 1912, was a Soviet military engineer who led the Night Witches regiment's engineering service and survived a 1942 death sentence, finishing the war a Guards captain.

Soft Actor-Critic

Soft Actor-Critic (SAC) is an off-policy, maximum-entropy actor-critic deep reinforcement learning algorithm for continuous control, introduced by Haarnoja, Zhou, Abbeel, and Levine at ICML 2018.